While waiting for an elevator at the Fair Oaks Mall near her home in Virginia recently, Janice Im, who works in early-childhood development, witnessed a troubling incident between a young boy and his mother.

The boy, whom Im estimates was about 2 1/2 years old, made repeated attempts to talk to his mother, but she wouldn’t look up from her BlackBerry.

"He’s like, ‘Mama? Mama? Mama?"’ Im recalled. "And then he starts tapping her leg. And she goes, ‘Just wait a second. Just wait a second."’

Finally, he was so frustrated, Im said, that "he goes, ‘Ahhh!’ and tries to bite her leg."

Much of the concern about cell phones and instant messaging and Twitter has been focused on how children who incessantly use the technology are affected by it. But parents’ use of such technology—and its effect on their offspring—is now becoming an equal source of concern to some child-development researchers.

Sherry Turkle, director of the Massachusetts Institute of Technology Initiative on Technology and Self, has been studying how parental use of technology affects children and young adults. After five years and 300 interviews, she has found that feelings of hurt, jealousy and competition are widespread. Her findings will be published in "Alone Together" early next year by Basic Books.

In her studies, Turkle said, "Over and over, kids raised the same three examples of feeling hurt and not wanting to show it when their mom or dad would be on their devices instead of paying attention to them: at meals, during pickup after either school or an extracurricular activity, and during sports events."

Turkle said that she recognizes the pressure adults feel to make themselves constantly available for work but added that she believes there is a greater force compelling them to keep checking the screen.

"There’s something that’s so engrossing about the kind of interactions people do with screens that they wall out the world," she said. "I’ve talked to children who try to get their parents to stop texting while driving and they get resistance, ‘Oh, just one, just one more quick one, honey.’ It’s like ‘one more drink."’

Laura Scott Wade, the director of ethics for a national medical organization in Chicago, said that six months ago her son, Lincoln, then 3 1/2, got so tired of her promises to get off the computer in "just one more minute" that he resorted to the kind of tactic parents typically use.

"He makes me set the timer on the microwave," Wade said. "And when it dings he’ll say, ‘Come on,’ and he’ll say, ‘Don’t bring your phone."’

Not all child-development experts think smartphone and laptop use by parents is necessarily a bad thing, of course. Parents have always had to divide their attention, and researchers point out that there’s a difference between quantity and quality when it comes to conversations between parents and children.

"It sort of comes back to quality time, and distracted time is not high-quality time, whether parents are checking the newspaper or their BlackBerry," said Frederick J. Zimmerman, a professor in the University of California, Los Angeles, School of Public Health who has studied how television can distract parents.

He also noted that smartphones and laptops may enable some parents to spend more time at home, which may, in turn, result in more, rather than less, quality time overall.

There is little other research on how parents’ constant use of such technology affects children, but experts say there is no question that engaged parenting—talking and explaining things to children, and responding to their questions—remains the bedrock of early childhood learning.

Betty Hart and Todd R. Risley’s landmark 1995 book, "Meaningful Differences in the Everyday Experience of Young American Children," shows that parents who supply a language-rich environment for their children help them develop a wide vocabulary, and that helps them learn to read.

The book connected language use at home with socioeconomic status. According to its findings, children in higher socioeconomic homes hear an average of 2,153 words an hour, whereas those in working-class households hear only about 1,251; children in the study whose parents were on welfare heard an average of 616 words an hour.

The question is, will devices like smartphones change that? Smartphone users tend to have higher incomes; research from the Nielsen Co. shows that they are twice as likely to make more than $100,000 a year than the average mobile subscriber. If increased use of technology encroaches on the time well-to-do families spend communicating with their children, some could become the victims of successes originally thought to help them.

Hart, who is now professor emeritus at the University of Kansas Life Span Institute, said more research is needed to find out whether the constant use of smartphones and other technology is interfering with that process, but she expressed hope that more parents would consider how their use of electronic devices might be limiting their ability to meet their children’s needs.

Part of the reason the children in affluent homes she studied developed larger vocabularies by the time they were 3 is that "parents are holding kids, the kids are on their lap while the parent is reading a book," Hart said. "It is important for parents to know when they’re talking to kids, they’re transferring affection as well as words. When you talk to people, there’s always an implicit message: ‘I like you,’ or ‘I don’t like you."’

Meredith Sinclair, a mother and blogger in Wilmette, Ill., said she had no idea how what she calls her "addiction to e-mail and social media websites" was bothering her children until she established an e-mail and Internet ban between 4 and 8 p.m., and her children responded with glee. "When I told them, my 12-year-old, Maxwell, was like, ‘Yes!"’ Sinclair said.

"You can’t really do both," she added. "If I’m at all connected, it’s too tempting. I need to make a distinct choice."

© 2010 The New York Times Company